Heating furnace



ocr. 22, 1929,

4 sheets-sheet 1 HEATING FURNACE Filed July 28. 192:5 4 sheets-sheet 2 oct. 22, 1929. n L, SUMMEY 1,732,916

HEATING'FURNACE Filed July 28, 1925 4 Sheets-Sheet 3 mme/Ot ,wb2/ZM Oct. 22, 1929. D, 1 suMMEY HEATING FURNACE Filed July 28. 1923 4 Sheets-Sheet 4 72 50770217 @RC1/Ir Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE DAVID L SUMMEY, F WATEBBURY, CONNECTICUT, ASSIGNOR SCOVILL MANUFAC- TUBING COMPANY, OF WATERBUBY, CONNECTICUT, A COREIOR'ATION 0F CONNECTI- CUT HEATING FURNACE vApplication led- July 28,

This invention relates to furnacesv for heat treating articles and more particularly to annealing furnaces.

It is the principal object of the inventlon to providev an effective and efficient heat-ing furnace, particularly an electrically heated furnace capable of annealing articles such, for example, as small brass shells.

With this general object in view the invention consists in the features, combinations, details of construction, and arrangements of parts which will first beV described in connection with the accompanying drawings, and then more particularly pointed out:

Fig. 1 is a longitudinal sectionalvlew, with parts broken awa of a furnace constructed in accordance wit the invention, the section being taken on the broken line 1-1 of Fig: 2;

Fig. 2 is a sectional view taken on the llne 2-'2 of Fig. 1;

Fig. 3 is a detail viewshowing part of Fig. 2 enlarged; l

Fig. 4 is a top plan view, with parts broken away and in section, of oneof the removable heating units;

Fig. 5 is a side view of the same with parts broken away and in section;

Fig. 6 is an end view, with parts in section,

looking in the direction of the arrow 6 1n Fig.ff4;

IFig. 7 is a sectional view taken on the line 7-"7 of Fig. 4:;l Fig. 8 is a detail view 'showin partly 1n section and partl in elevation t e manner of connecting the uckets;

' Fig. 9 is a sectional view taken on the line 9 9 of Fig. 8; v Fig. -10 is aview'n side elevation of one of the shackles removed;

Fig. 11 is an enlarged view partly in side elevation and with parts broken away and in section, of part of one side wall of the heating chamber, looking in the direction of the arrow 11 of Fig. 2;

Fig. 12 is a sectional view taken on the line 12--12 of Fig. 11;

Fig. 13 is a ing block removed;

Fig. -11.1. is a similar'view of a bracket; and

Figs. 15, 16 and 17 arawiring diagrams.

-and a brass shells, for exam le.

perspective view of a supportv 1923.' serial No. 654,295:

Referring to the drawings, there is lprovided a substantially closed furnace housing having a heating chamber. As here shown as an example, the furnace comprises a main housing) 20l1aving side walls 21, a top` arch 22 ottom wall 23. These elements are here shown in a conventional manner only and may be of any suitable construction. An intermediate arch 2,4 divides the interior of the main housing into the parallel longitudinalchambers 25, 26, running from end to end of the housing. As later described the upper chamber has heating means and may be termed the heating chamber. At one end of the furnace (the left end in Fig. 1) the. cham- -bers 25, 26 open into a charging chamber 27 enclosed'by a supplemental housing or hood 28 which seats on the foundation 29. At the opposite end, a second supplemental housing or hood 3() encloses a discharge chamber 31, into which-the longitudinal chambers open.

There is provided means for conveying the articles to be heated through the heating chamber of the furnace and in structures embodying the invention to the best advantage,

the articles are moved by an' endless conveyor,

enclosed by the furnace housing. Although capable of various constructions, in the present embodiment, the conveyor comprises an endless chain of buckets 32 connected together as `later described. These buckets are arranged with their longer axes parallel to one yanother and transverse to the furnace chambers. Each bucket is `designed to hold a relatively large mass 'of small articles, such as In the charging chamber 27 are two exagonal 'pulleys 33 mounted on a suitabl journaled horizontal shaft 34, the faces of these pulleys being arranr d to receive the bottoms of the buckets." In t edischarge chamber 31 are two similar pulleys 35 mounted on a suitably journaled horizontal shaft 36. As appears in Fig. 1, the bucket chain, between the pulleys, has an upper strand of upright buckets and a lower strand 0f inverted buckets.' In the furnace shown, this upper strand travels through the heatingchamber 26, being slidable on rails 37 supported on T-beams 38 and illars 39 from the intermediate arch. T c lower strand travels in the reverse direction in the return chamber 26, the inverted buckets sliding on rails 40 supported by T-beams 41 from the bottom wall of the furnace housing. As appears in Fig-1, both sets of rails extend into the end chambers in proximity to the pulleys so that the buckets can readily pass rom pulleys to rails and from rails to pulleys. There is provided means for driving the conveyor, preferably with a continuous movement. As here shown as an example, on the shaft 36 is a gear 42 meshing with a pinion 43 on a stud 44. The latter is rotated by a worm wheel 45 meshing with a worm 46 coupled to a motor 47. This motor is operated so as to drive the chain of buckets at such a speed as to enable the heat treatment to be accomplished, the upper strand moving from the charging to the discharging end of the furnace, that is, from left to right as viewed in Fig. 1.

There is provided means whereby the articles may be delivered to the bucketswhile in the charging chamber. As here shown as an example, in the top hood 28, above the first upright bucket, is a charging spout- 52 through which the articles may be delivered to the charging chamber, falling by gravity to the bucket beneath. The spout has a normally closed door or gate 53 which may be opened to permit the articles to be delivered to the buckets. If desired, automatic charging means such as shown in a copending application, Serial Number 654,294 (now Patent No. 1,554,241, Sept. 22, 1925) maybe employed. Although the buckets described have a continuous movement, this movement is so slow a bucket may be readily filled as it passes beneath spout 52.

There is provided, adjacent the discharge end of the furnace a tank for containing a cooling liquid into which the articles are delivered from the buckets after being heated. As here shown as an example, beneath the discharge hood 31, extends a tank for containing a cooling liquid, for example, water. As the buckets turn down over pulleys 35 and approach an inverted position, the heated articles fall out by gravity and drop into the cooling liquid which cushions their fall and quenches them. The articles are confined in a small area in the .tank by a funnel 54 and may be removed in any suitable manner, for

example, by the means shown in the copending application referred to.

The water or other liquid in the-. tank also serves as a seal for the discharge chamber,'

thereby conserving heat and excluding air.

There is provided means for heating the articles during their travel through the heating chamber and in structures embodying the invention to the best advantage, the path of the upper strand of the conveyor is surrounded by heating elements. The invention in its entirety also includes heating elements indi- These supports are rectangular blocks formed of refractory and insulating material, such as fire brick, and are formed with a series of parallel grooves 62. Supported by the blocks are electric resistor wires 63 made, for example, of nickel-chromium alloy and arranged in a series of reverse hairpin bends (Fig. 11) laid in the grooves 62. As shown, four wires are provided for the side of the heating chamber, two wires being carried by the Aupper row of blocks 61 and two by the lower row. Each Wire has its loops extending longitudinally of the furnace across several supporting blocks (Fig. 11) so that two alined wires are coextensive with the heating zone. Also suspended in the T-brackets 60 are blocks 64 located between the supporting blocks 61 and the heating chamber. As shown, these blocks 64 are duplicates of the supporting blocks 61. The blocks 64 serve as covers for` the resistors and with the construction shown the grooves give a large heat radiating surface and manufacturing cost is reduced.

Adjacent one end of a row of supporting blocks 61 the ends oftwo of the resistor wires are turned outwardly and terminate in leads 65 passing through suitable passageways 66 in the furnace side wall and connected to bus bars 67, 68 outside the main housing (Figs. 2 and 3). As shown, the leads 65 are of a substantially greater cross section than the looped wires 63. The leads 65 and wires 63 may be integral or may be formed separately and welded or otherwise connected together. With the construction described the heating effect of the leads is materially reduced and concentration of heat in the furnace walls is avoided.

At the opposite end of the supporting blocks, the ends of the other two resistor wires are connected to the bus bars in the manner above described and shown in Figs. 2 and 3. While the leads for these wires are not shown, they are indicated at 69 in the Wiring diagram of Fig. 17. As there shown the bus bars 67, 68 are connected to conductors 70, 71 which leads to a suitable transformer and current source (not shown);

The heating means adjacent the other side wall of the heating chamber is, in the present embodiment, a duplication of the heatvided for the top ofthe heating chamber. To

this end, as here illustrated as an example,

set in the inner wall of the arch 22, are seven longitudinal ro'ws of T-brackets 60 and suspended in these brackets are siX rows of complementary supporting blocks 61 and cover blocks 64 arranged in the manner described in connection with the side heaters. Supported inthe grooves of the blocks 61 are resistor Wires 74 arranged like Wires 63, that is, in a series of reverse hair-pin bends or loops. The top heating means is not shown in detail but it is indicated in Figs. 1 and 2 and Fig. 15 shows twelve wires. That is, for each row of supporting blocks there are provided two Wires, the loops of each running from one end toward the middle, the two alined wires being substantially coeXtensive with the heating zone.

At one end of the row of blocks, that is, near one end of the furnace, the ends of six Wires are turned upwardly, and terminate in leads 75 (Fig. 2) passing through suitablel passageways 7 6 in the arch 22 and connected to bus bars 77, 78 outside the main housing. As in the case of theleads 65, the leads 75 are of an increased cross-section to prevent concentration of heat in the furnace wall. At the opposite end of the row of blocks, the other six wires are similarly connected to bus bars 79, 80, leading to a suitable transformer and current source (not shown). One lead 81 for this end of the arch is shown in Fig. 1 and the others are indicated in the diagram of Fig. 15, it being understood that they are like the leads 7 5 shown in Fig. 2.

It is to be understood that any suitable number of resistor wires may be used at both the top and sides of the heating chamber, the ninber here shown being by wayl of exam- P As above stated, the invention in its entiret includes electric resistance elements indivi ully removable from the outside of the furnace. In the present embodiment of the invention, the removable heating elements are those located between the strands of the conveyor and they are removable while the conveyor is in place. This may be accomplished, for example, by means of individual heating units slidable transversely of the furnace along a suitable supportwhichwith the type of furnace described, may include the intermediate arch. Although capable of various constructions, in that here shown as an example, associated with the bottom of the heating chamber 25, are a number of transverse passageways 90. separated by the pillars 39 and opening at the top into the heating cham'- ber. These passages extend across 'the bottom of the heating chamber and at one end, the left in Fig. 2, they penetrate the side wall of the main housing. At the bottom of these passages are bearing plates 91Which may be suitably made of carborundum, and which are supported, in part, by the intermediate arch 24.

Slidable in each passage along the bearing plate 91, is a removable heating unit and in structures embodying the invention to the best example, this unit comprises a supporting blocka resistor wire, a cover block and an element for binding the blocks together so as to form a manipulable assembled unit. As here shown as an example, the resistor is a nickel-chromium alloy `wire 92 arranged in a series of reverse hair-pin bends and supported in the grooves 93 of a refractory insulating supporting block, similar' to the block 61 above described. Over the supporting block and its Wire is placed a refractory insulating cover block similar to cover block 64. The assembled blocks are carried by a skeleton metal frame 96 of an inside capacity to freely but firmly t the superposed blocks. In the frame shown one end is closed, the other end open. To assemble the unit, the superposedblocks are slid into the open end of the frame until they engage the closed end. The open end is then closed to retain the blocks in place. To this end, as here shown as an example, after the blocks are inserted in the frame, a closure plate 98 is inserted in the open end of the frame. This plate is'of a size to fit within the end of the frame 96 and its lower corners are cut away, as at 99, to permit passage of the ends of the wire. Outside the closure plate are two headed pins 100 Which are dropped through suitable alined holes in the top and bottom of the frame.

, lVhen the plate 98 and pins 100 are in place the blocks are held in place in theframe and the entire assembled unit is readily moved about. The ends of Wire 92 are integral with or connected to leads 101 of an increased diameter as in the case of the leads above described. The unit as a Whole, as appears in Fig. 2, is of a length slightly less than the Width of the heating chamber. When in place, the unit extends across the bottom of the chamber between the two strands of buckets and just below the buckets of the Yupper conveying strand.

In assembling the furnace, the unit described is slid along passage 90 on the bearing plate 91 until the frame is positioned by being stopped at the end of the passage (Fig.

2). To close the passage, after insertion of the unit, as here shown as an example, the end of the passage 90 is plugged by a number of perforated bricks 102 which are inserted in the passage, the leads 101 passing through the perforations. Fire clay may be'used to lute the oints. Beyond the outside brick the leads are connected by a coupling 103 to conductors 104 connected to bus bars 105, 106 leading to a suitable transformer and current source (not shown). y'lo remove the unit, for repairs, substitution or the like, the fire clay and bricks 102 are raked out, ,whereupon the heating unit may be pulled out of the passage along the bearing plate. The unit itself is readily disassembled by removing the pins 100 and plate 98. With the construction described, the heating unit is readily manipulable and a unit may be removed and replaced from outside the furnace and While the conveyor chain is in placel As appears in Fig. 1, units are provided to extend substantially from end to end of the heating chamber. As here shown, there are twelve heating units such as that described, these units being duplications except that three sets of bus bars are provided, as appears in Fig. 16. The bus bars 105, 106 receive the leads from the first four units from the left as viewed in Figs. 1 andI 16. Bus bars 107, 108 receive the leads of the next four Wires and bus bars 109, 110 receivethe leads of the last four wires.

In the construction described, with the conveyor chain enclosed by the housing and the idle return strand returning through the lower chamber 26, there is a material economy in heat requirements. lVhile there is a drop in the temperature of the buckets, the temperature is held up to such a point that it may be brought back to the heat treatment level without excess heat input. If desired, the return chamber may be heated also, in order to further reduce the drop in the temperature of the buckets. For example, the heating means above described may be duplicated by the lower chamber. In connection with the conservation of heat, it is noted that any of the passages ,for leads or other furnace openings may be luted with fire clay.

The buckets of the conveyor chain are connected ltogether in a manner to permit the chain movement under conditions in which ordinary lubrication is impossible.

As here shown as an exam le, the buckets have on one side a pair of peribrated lugs 120 andn on the other side a pair of perforated yokes 121. The buckets are connected together in the form of a chain by assembling the buckets with the yokes 121 of one bucket straddling the lugs 120 of the adjacent bucket a 1 1d passing pivot pins 122 through the alined .perforations In the present embodiment these -p'ins have the form of plain cylinders and are of'a length to extend beyond the over- ..lappi1'ig yokes and lugs at each end. They are made of a metal having Wearing qualities and capable of withstanding continued high temperatures. For this purpose nickel-chromium alloy is suitable. The buckets in the present embodiment are also made of nickel-chromi-y um alloy. With the construction described the buckets areconnected in theiorm of an vendless chain in a simple manner and the As here shown as an example, the ends of ,to a size considerably smaller than the diameter of the pivot pin. With this construction the end of the shackle acts as a stop against endwise movement of the pin in one direction as the pin cannot pass the reduced opening, but the opening permits access to the pin to drive it out in the other direction. The other end of the shackle has bore 125 of a size to pass the pin for assembly or disassembly. To block this bore to prevent endwise movement of the pin, as here shown as an exam le, the end of the shackle has a boss 126 W ich is drilled with two holes (shown in Fig. 9) at right angles to the axis of bore 125 and so located that each hole grooves the wall of bore 125. Insertable in the open end of the bore after the pivot pin is assembled is a cylindrical plug 127 of substantially the same diameter as the pin. This plug is grooved to form, in connection with the grooves in the Wall of bore 125, passageways for locking pins 128. These locking pins are inserted through the holes formedin boss 126 and lock the plug 127 in place. With the construction described, the'4 shackles hold the pivot pins in place and the pins cannot drop out nor can pieces drop out ifa pin breaks. The parts, however, are readily disassembled and reassembled -for repairs and the like and there is no interference with the pivotal movements of the pins.

As above stated, the buckets and their pivot pins are made of a material that will retain its physical strength under continuedahigh temperatures, for example, nickel-chromium alloy-a material having the same heat resisting characteristics as the resistor Wires.

In the furnace here illustrated, the shackles 123 and their associated parts, the upper rail-s 37, the T-beams 38, the skeleton frames for the removable heating units, and the discharge pulleys 35 are also made of nickelchromium alloy.

There` is provided means whereby the ticles under treatment may be subjected to an oxidizing action and in structures embodying the invention to the best advantage this oidizin'g takes place during the early part o the travel through the heating chamber and thereafter the articles are subjected to a noni-.oxidizing atmosphere. In the present embodiment of the invention, although the furnace housing is substantially closed, there is, some air leakage, for example, through the intermittently opened charging gate and around the chai-gin `pulley shaft.

a stack for drawing off the furnace gases. The draft createdcauses a slight flow of air from the charging end of the furnace toward the discharging end. In'the pipe 131 is a regulable damper 132 for controlling the draft. To permit the circulating air to oxidation of the oil or soap solution with which the articles may be coated and so prevents stains on the treated articles. By the time the articles travel well into the heating chamber and become highly heated the oxidizing air has been largely replaced by furnace gases and steam from the cooling tank. Consequently, after the earlier part of the heat treatment the articles are subjected to a substantially non-oxidizing atmosphere. The damper is kept as nearly closed as possible to obtain just enough draft to effect the desired result. Should the treated articles come out stained, the damper is opened slightly and an increased oxidation results. While the ipe 131 is shown in the end wall of the disc arge chamber it may, of course, be located at any suitable point, for example, in the to wall.

The operation o the furnace will be clear tfrom the above without further descriplon.

What I claim is:

1. In a furnace for heat treating metal articles, and in combination, a furnace housing having two longitudinal chambers and two end chambers communicating therewith, an endless chain of conveyor buckets having one strand advancing through one longitudinal chamber and the other strand returning through the other longitudinal chamber, pulleys over which the conveyor runs, located in said end chambers, a tankadjacent the discharge end of the furnace below the path of the conveyor chain for containing cooling liquid into which the articles fall as the buckets pass down over theirpulleyand which forms a seal for the bottom of the end chamber, and heating means for the first longitudinal chamber.

2. In a furnace for heat treating metal articles, and in combination, a furnace housing having two longitudinal chambers and two end chambers communicating therewith, an endless chain of conveyor buckets having one strand advancing through one longitudinal chamber and the other strand returning through the other longitudinal chamber, pulleys over which the conveyor runs located in said end chambers, a tank adjace t the discharge end of the furnace below t e path of the conveyor chain for containing cooling liquid into which the articles fall as the buckets pass down over their pulley, a gate in the housing for the delivery of the articles tothe buckets while in the other end chamber, and

heating means for the rst longitudinal chamber.

3. In a furnacefor heat treating metal articles, and in combination, a substantially.

closed furnace housing having a heating chamber, heating means therefor, a plurality of buckets for conveying the articles through said heating chamber, said buckets having holes therein for the passage of a gas, an exhaust pipe associated with the discharge end of the furnace, and a regulable damper for said exhaust pipe.

4. In a furnace for heat treating metal articles, and in combination, a substantially closed furnace housing having a heating chamber, heating means therefor, conveyormeans for moving thelarticls through said heating chamber, a tank adjacent the discharge end of the furnace for containing a` liquid finto which the articles are freely dropped from the conveyor and which forms a seal with the housing to exclude air, an exhaust pipe associated withv the discharge end of thev furnace, and a regulable damper for` 5. In a furnace for heat 'treating metal articles, and in combination, a substantially closed furnace housing having a heating chamber, heating means therefor, conveyor means for moving the articles throu h said heating chamber, a tank adjacent t e discharge end ofthe furnace for containing a liquid into which the articles are' freely dropped from the conveyor and which forms a seal with the housing to exclude air, and an exhaust pipe associated with the discharge end of the furnace. 6.' In a furnace for heat treating metal articles, and in combination, a furnace housing having a substantially closed furnace chamber, heating means associated with said chamber, conveyor' means for conveying the articles through the furnace chamber, means whereby a draft of air may be caused to pass through the furnace chamber, and a cooling tank, located at the discharging end of the furnace chamber and within the housing, for containing a cooling liquid into which the heated articles are discharged, whereby the articles are subjected to the oxidizing action Y of the air at the start of their travel through the chamber but are largely protected from such oxidizing. action atthe end of their v travel by steam formed in the cooling tank.

7 In a furnace, and in combination, a furnace housing having a lsubstantially closed furnace chamber, a plurality of conveyor buckets for 1..conveying articles to be heated Y through the furnace chamber, heating means associated with the furnace chamber, and means whereby a draft of air may be caused to pass through said furnace chamber, the buckets having holes to permit access of air to the conveyed articles, whereby the articles may be subjected to an oxidizing atmosphere.

In testimony whereof, Ihave hereunto set my hand. n

DAVID L. SUMMEY. 

